In general, a display device such as a LCD, PDP or the like should have a stand that supports a monitor, specifically, a display part and the display device can be usable on a desk or table. The stand is secured to a rear surface of the monitor by means of a hinge assembly. Thus, a user can adjust an angle of the monitor as he/she wants. Recently, such display devices have been under development, as a user can conveniently adjust the height of a monitor provided in as he/she wants to enhance convenience.
Referring to FIGS. 1 and 2, a conventional display device having an angle/height adjustment function will be described.
A conventional display device includes a monitor 1, a stand 2 and a base 3. The monitor 1 displays images and the stand 2 is fastened to the monitor 1. The base 3 supports the stand 2 on a surface of a desk or table.
The monitor 1 is vertically sliding movable and installed on a connecting block 4 connected to an upper end of the stand 2. The connecting block 4 is rotatably fastened to the stand 2 by a hinge assembly 2 installed at an upper end of the stand 2 and the connecting block 4 is rotatable forwardly/downwardly about a hinge assembly 2. Thus, when a use moves the monitor 1 forwardly/downwardly, the connecting block 4 rotates about the hinge assembly 5 and the angle (θ) of the monitor 1 is adjusted.
An elastic member (not shown) such as a spiral spring is provided in the connecting block 4. The elastic member supplies an elasticity corresponding to the load (W) of the monitor 1 to the monitor 1 and it supports the monitor 1 at a predetermined height. The spiral spring uniformly supplies a predetermined elastic force (F) to the monitor 1 to support the monitor 1, regardless of displacement. Thus, when the user vertically moves the monitor 1 with respect to the connecting block 4 and the external force applied to the monitor 1 is removed, the monitor 1 keeps its position due to the elastic force of the spiral spring.
A lower end of the stand 2 is hingedly fastened to the base part 3 by a lower hinge assembly 6 and the stand 2 is rotatable about the base part 3.
However, the conventional display device has following problems.
As shown in FIG. 1, when the monitor 1 is not oblique to the stand 2, the load of the monitor 1 is only vertically downward. The load (W) of the monitor 1 is substantially the same as the elastic force (F) of the spiral spring (not shown) supporting the monitor 1 on the connecting block 4.
However, as shown in FIG. 2, if the user rotates the monitor 1 backwardly to adjust the angle (θ) of the monitor 1 at more than a predetermined angle, a center of the monitor gravity is moved and a component of force is changed. Thereby, the balance between the elastic force (F) of the spiral spring (not shown) and the load of the monitor 1 in a direction of the elastic force (F) is lost.
More specifically, when the monitor 1 rotates at an angle (θ), a load (W1) of the monitor 1 corresponding to the elasticity of the spiral spring (not shown) is W cos θ, which is smaller than the elasticity (F) of the spiral spring (not shown). Accordingly, there might be an Auto-lift-up which means that the monitor moves upward slightly due to the elasticity of the spiral spring. If the auto-lift-up occurs, the angle of the monitor may not be adjusted as a user wants.